1. Field of the Invention
This invention is concerned with the conversion of biological material to hydrocarbons. More particularly, it is concerned with the manufacture of hydrocarbon fuels and chemicals from organic products produced by plants and animals. By the process of this invention, such organic products are catalytically transformed to high quality fuels and chemicals. This invention is further concerned with a catalytic process whereby raw material produced by living matter is converted to gasoline or other liquid hydrocarbon fuel with high energy effiency.
2. Prior Art
There is currently a lively interest in finding economical sources other than petroleum for liquid fuels and hydrocarbon chemicals. It is well known, of course, that methanol may be produced from coal and ethanol by fermentation of sugars. However, both of these processes are costly and considerably more than one gallon of alcohol is needed to provide the energy available from a gallon of liquid hydrocarbon such as fuel oil. Gasoline may be made from coal, but again the cost is high and the gasoline as produced is of poor quality.
Several unconventional ideas have been proposed to convert plant materials to fuels and chemicals. A summary of these proposals is listed in a chapter entitled "Fuels and Chemicals from Crops" in the book by L. L. Anderson and D. A. Tillman "Fuels from Waste", Academic Press, New York, 1977; the entire contents of said chapter is incorporated herein by reference for background purposes. The processes include anaerobic digestion to produce methane, fermentation, gasification and pyrolysis.
In general, the prior art processes suffer from several disadvantages. They usually produce a plurality of product streams that require separate handling, by-products of low value, and a stream that requires disposal. For example, anaerobic fermentation, in addition to methane, yields a solid sludge and a waste liquid stream. Pyrolysis of wood produces a mixture of organic compounds, gases, tars and char, as well as a contaminated aqueous stream. Fermentation of starch or sugar can yield ethanol, acetone, butanol or a number of other organic chemicals. However, since fermentation requires the desired product to be formed in dilute aqueous solution, distillation is required which is not only costly but also requires considerable energy. As a result, the net yield of useful fuel or chemicals that may be realized from an acre of agricultural effort by fermentation is quite limited.
For example, in ethanol production from corn, the typical total biomass of corn growth on an acre may have a fuel value equivalent to 600 gallons of gasoline. The fermentation and distillation sequence yields only about 25% of that energy, or ethyl alcohol product equivalent to 150 gallons of gasoline. The fermentation-distillation sequence itself requires fuel, and this fuel requirement can exceed the amount of fuel value produced as alcohol. New technology can reduce this fuel requirement, or it can conceivably be eliminated by using farm waste. However, the agricultural effort alone, including its industrial support (fertilizers, chemicals, tractors, machinery) requires fuel equivalent to about 92 gallons. Thus, while the apparent productivity is equivalent to 150 gallons of fuel (as ethanol) at the plant, the net amount won is only 58 gallons of fuel equivalent. In addition, corn production requires high quality agricultural land. In brief, there is evidently a need for efficient methods by which substances produced by plants or animals may be converted to high quality hydrocarbon fuels and chemicals.